added default unmapper functions for OfMap

- removed Search

filter.go

@@ -9,3 +9,30 @@ func Filter[T any](slice []T, f func(T) bool) []T {
 	}
 	return ret
 }
+
+func FindFirst[T any](slice []T, f func(T) bool) (T, bool) {
+	for _, v := range slice {
+		if f(v) {
+			return v, true
+		}
+	}
+	return *new(T), false
+}
+
+func FindFirstIndex[T any](slice []T, f func(T) bool) (int, bool) {
+	for i, v := range slice {
+		if f(v) {
+			return i, true
+		}
+	}
+	return -1, false
+}
+
+func FindLastIndex[T any](slice []T, f func(T) bool) (int, bool) {
+	for i := len(slice); i >= 0; i-- {
+		if f(slice[i]) {
+			return i, true
+		}
+	}
+	return -1, false
+}

go.mod

@@ -1,3 +1,5 @@
 module git.milar.in/milarin/slices
 
 go 1.19
+
+require git.milar.in/milarin/gmath v0.0.3

go.sum

@@ -1,2 +1,2 @@
-git.milar.in/milarin/channel v0.0.7 h1:cVKtwgH/EE7U+XTHcoFCClJ4LR349KanzjX9xKwRcNg=
+git.milar.in/milarin/gmath v0.0.3 h1:ii6rKNItS55O/wtIFhD1cTN2BMwDZjTBmiOocKURvxM=
-git.milar.in/milarin/channel v0.0.7/go.mod h1:We83LTI8S7u7II3pD+A2ChCDWJfCkcBUCUqii9HjTtM=
+git.milar.in/milarin/gmath v0.0.3/go.mod h1:HDLftG5RLpiNGKiIWh+O2G1PYkNzyLDADO8Cd/1abiE=

map.go

@@ -7,3 +7,15 @@ func Map[I, O any](slice []I, mapper func(I) O) []O {
 	}
 	return ret
 }
+
+func MapError[I, O any](slice []I, mapper func(I) (O, error)) ([]O, error) {
+	ret := make([]O, 0, len(slice))
+	for _, old := range slice {
+		new, err := mapper(old)
+		if err != nil {
+			return nil, err
+		}
+		ret = append(ret, new)
+	}
+	return ret, nil
+}

of.go

@@ -14,3 +14,15 @@ func OfMap[K comparable, V, T any](m map[K]V, unmapper func(K, V) T) []T {
 	}
 	return out
 }
+
+// UnmapKey is an unmapper function which returns the map key only
+// and discards its value. It is supposed to be used with OfMap
+func UnmapKey[K comparable, V any](key K, _ V) K {
+	return key
+}
+
+// UnmapValue is an unmapper function which returns the map value only
+// and discards its key. It is supposed to be used with OfMap
+func UnmapValue[K comparable, V any](_ K, value V) V {
+	return value
+}

reduce.go

@@ -0,0 +1,15 @@
+package slices
+
+import "git.milar.in/milarin/gmath"
+
+func Reduce[T, R any](slice []T, reducer func(current R, v T) R) R {
+	res := new(R)
+	Each(slice, func(v T) {
+		*res = reducer(*res, v)
+	})
+	return *res
+}
+
+func SumReducer[N gmath.Number](a, b N) N {
+	return a + b
+}

reduce_test.go

@@ -0,0 +1,11 @@
+package slices
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestReduce(t *testing.T) {
+	s := Of(1, 2, 3)
+	fmt.Println(Reduce(s, SumReducer[int]))
+}

search.go

@@ -1,11 +0,0 @@
-package slices
-
-func Search[T any](slice []T, f func(a, b T) T) T {
-	if len(slice) == 0 {
-		return *new(T)
-	}
-
-	value := slice[0]
-	Each(slice, func(v T) { value = f(value, v) })
-	return value
-}